Widget Editor: Fix allow adding same image twice (#32951)

* Widget Editor: Fix allow adding same image twice

* remove duplicate reference widget instances only for legacy widgets

* update id check

Co-authored-by: Kai Hao <[email protected]>

Co-authored-by: Kai Hao <[email protected]>

Author: thisissandip

packages/edit-widgets/src/store/actions.js

@@ -108,10 +108,15 @@ export function* saveWidgetArea( widgetAreaId ) {
 		( { sidebar } ) => sidebar === widgetAreaId
 	);
 
-	// Remove all duplicate reference widget instances
+	// Remove all duplicate reference widget instances for legacy widgets.
+	// Why? We filter out the widgets with duplicate IDs to prevent adding more than one instance of a widget
+	// implemented using a function. WordPress doesn't support having more than one instance of these, if you try to
+	// save multiple instances of these in different sidebars you will run into undefined behaviors.
 	const usedReferenceWidgets = [];
-	const widgetsBlocks = post.blocks.filter( ( { attributes: { id } } ) => {
-		if ( id ) {
+	const widgetsBlocks = post.blocks.filter( ( block ) => {
+		const { id } = block.attributes;
+
+		if ( block.name === 'core/legacy-widget' && id ) {
 			if ( usedReferenceWidgets.includes( id ) ) {
 				return false;
 			}